Gear finishing machine



July 12, 1938.

Original Filed July 31, 1931 INVENTOR.

. 2 ENE? l i iw 6 M 5 @mg -.I- m l o l 70 0 10 WW f O O 2 a J 1 T T Z ATTORNEE.

Patented July 12,

UNITED STATES PATENT OFFICE GEAR FimsmNG MACHINE William F.Dalzen, Grosse Pointe, Mich, assignor to Michigan Tool Company, a

Delaware eerporation of Original application July 31, 1931, Serial No. 554,193. Divided and this application August 1,1935. Serial No. 34,139

wherein the cutter and the gear blank are 'ro-' tated in timed relation. Expensive machines, which were extremely accurate, were employed for supporting the cutters and the blanks in an attempt to eliminate errors in the tooth profile and spacing. -While the errors are reduced to a minimum, nevertheless, owing to the variation in the hardness of the material at difi'erent points about the gear blank andalso because 01' slight machineerrors which are impossible to eliminate,

'the spacing and the profile of the teeth are not entirely uniform when generated by the present known methods. I

When my cutting tool is employed, a gear may be generated which is. extremely accurate be- !5 cause of the accuracy with which my tool may be constructed and operated. The profile 01 the teeth of the cutting tool may be constructed to' be exactly the same on both sides and the spacing is, in like manner, made to beexaet, so that the gears which are finished by my cutting tool will accurately mesh therewith and with each other. The employment of my cutting tool eliminates any machine errors from efiecting changes in the tooth contouror spacing, as the errors of themachine cannot be introduced between the cutter and gear blank. For this reason the expensive machine above referred to need no longer be employed for gear tooth generation and an extremely simple and inexpensive machine may be utilized for effecting the manipulation of my gear cutter.v

When a formed cutter or grinding wheel is employed for generating teeth' on gears, the teeth formed thereby are inaccurate because the cutters 45 for grinding wheels are only approximate in contour below the base circle which is well known to be within the working depth of the gearteeth. My present cutter reaches to thei'ull tooth depth and accurately machines a correct profile, re- 50 gardless of the gear diameter, pitch or pressure angle, and regardless of whether ornot the base 65 remain in contact with a' greater number .0!

7 Claims. (Q1. 90 -2) teeth on my cutting tool than will be in contact I with a second gear generated in like manner by the tool, and interference between the teeth of the two gears will be impossible,

Accordingly, the present invention has for its main objects: to provide apparatus for machining teeth on a gear blank of accurate predetermined contour and spacing throughout the entire periphery oithe gear; apparat for machining teeth on gears which effects an arcuate, lateral-movement between the teeth when the cutter and gear are moved longitudinally when in meshed relation; the provision 01: a machine which supports a gear relative to a cutter in such manner as to effect a lateral movementboth to the cutter and the gear blank as the blank is rotated relative to the cutter; and, in general, to provide apparatus for machining agear which apidly cuts the teeth ,toaccurate dimensions hrougli the arcuate lateral movement providedbetween the teeth of the cutter and those of the gear effected on a machine which is simple in construction and operation and which provides an exceptionally fine finish on the sides of the teeth which are of extremely accurate di .mensions.

Other objects and features-of novelty of my invention will be either specifically pointed out or become apparent when referring, for a better understanding of my invention, to the. following description in conjunction with the accompanying drawing, wherein:

Figure, 1 is a view in elevation of a gear cutting machine embodyingfeatures of my invention,

Fig. 2 is a brokensectional view of the structure illustrated in'Fig. 1, taken on the line 2-2 there,-

of, v

Fig. 3 is a sectional view of the structure illustrated in Fig. 2, taken on the line 3-3 thereof,

ture illustrated in 1' showing a gear went by a modified form thereof, and

Fig. 6 is a view similar to 5 showing a further modified form of gear cut by structure embodying invention.

In my co-pending application, Serial -No.

554,192, filed July 31, 1931 and assigned to the assigneeoi-the present invention, I have illustrated a cutting tool which is made up from a plurality of blades uponthe ends oiwhich teeth are provided of predetermined contour, having cutting edges disposed on the sideslor the teeth and in some instances across their top edges. The teeth are disposed in rows, which may beextended laterally or angularly acrossa channel a shaped holder, in which the blades are retained in tions i1 and I8 which form a central recess IS.

A plurality of blades 2| are disposed in the recess I9 eitherlaterally or angularly relative to the upstanding side portions I1 and I8, as pointed out above. A wedge member 22 engages sloping sides of the blades 2i, as illustrated in Fig. 3, and is drawn downwardly in th'erecess by a plurality of screws 23, the heads of which engage recesses 24 provided in the wedge member. End plates 25 are disposed in slots 26, provided in the ends of the upstanding portions IL, and I8, for closing the ends of the recess l8 when supported in fixed relation to the holder- I 5 by bolts 21. A bolt 28 extends through aperture 29 provided through the blades, as'illustrated in Fig. 3, for supporting the blades on the end plates 25. A wedge member 3i, having a sloping surface in engagement with a sloping surface of one of the plates 25, forces the blades 2 I into intimate longitudinal reiationwhen a screw 32, disposed inan elongated aperture 33 in the wedge member, is tightened.

The cutter i4 isattached to a slidable plate 34 of truncated conical section, the sloping sides thecutter H, which is retained by bolts 38 r in fixed relation to the plate. An arm 39 proiects upwardly from the base plate 35 having a laterally extending portion 4! on its upper end, which is bifurcated to receive a hand wheel 42 through which a threaded end 43, of a gear blank supporting member 44, extends. The turning of the hand wheel 42 raises and lowers the member 44 relative to the cutter i4 for pcsitioning the gear blanks relative to the teeth of the cutter. The ,lower end of the member 44 is bifurcated, havingdownwardly extendingside portions 45 and 46 through which aligned apertures extend for receiving a spindle 48 for supporting ,a gear blank 48 in the space between the downwardly extending portions, 45 and 46 44 is grooved at ii in which an inwardly ex tending tenon 5'2 of a washer 53 registers, for

the purpose of ipgularly positioning the member flgelative to the cutter II. A screw 54 extendin: through a slot in the washer 53 is tightened to draw the washer into fixed relation to the top surface of the extending portion 4| of the projecting. member 38. I Figs. 1 and 2 a spur gear 49 supported by the member 44 with the laterally disposed teeth thereof in niesh with the teeth 2| of 'the. tool i4. The teeth of the cutting tool l4 are disposed at anangle for the purposeiof'having the gear I have illustrated in blank disposed angularly relative to the movement of the cutter for effecting a relative lateral movement between the teeth of the cutter and gear for machining the sides of-the gear teeth' when the cutter is moved longitudinally.

The hand wheel 42 is operated to force the gear blanks to intimate contact fl; t

"effected bythe operation of the hand wheel 42.

When the center of the spindle 48 has moved downwardly until it is disposed a predetermined distance above the cutting teeth, the gear is then machined to a predetermined diameter having teeth of accurate predetermined shape and dimensions. s

As pointed out in my above mentioned 00- pending application, the cutting of the teeth is effected by the cutting edges provided on the sides of the teeth of the tool. The cutting edges are formed by a plurality of grooves disposed edge of the teeth, as illustrated in Figs. 3 and 4,

for effecting cutting edges 51 at the top of the teeth in addition to the cutting edges 58 provided on their sides. The angular disposition of the gear blank relative to the movement of the cutter effects a lateral movement between theengaging sides of the teeth during the rotation of the blank, through its longitudinal movement or that of the cutter, to machine the sides of the gear teeth as they pass across the cutting edges 51 and 58 of the cutter teeth.

In Figs. 5 and 6 I have illustrated right and left handspir'al gears, that is to say, gears having angularly disposed teeth which may slope in either direction as shown in the figures. when spiral gears of this type are to be cut by my cutting tool, 'I dispose the blades 2i laterally across'the channel shaped member I5 and likewise angularly dispose the gear blank whensupe ported by the member 44, to have the teeth of the blank register with the teeth of the cutting tool. The angular), disposition between the top of the cutting teeth, the gear blank may be.

mounted directly upon the member 44 without first roughing out teeth in the periphery thereof, the roughing operation being eifected by the cutting edges 51 and 58 of the cutter. While a complete cutting operationfor machining teeth .in the gear blank may be effected by my cutting tool, it is to be understood that the tool operates more efflciently in finishing the teeth after they have first been roughed out by a hobbing or like cutting operation. L t

This method of roughing and fl l fl gear:

is capable of ng extended through the employment of a circ ar cutter in place of the flat cut- 'ter herein described and illustrated. An arbor i s provi'ded for supporting and rotating the cutterwhich is substituted for the mechanism for longitudinally moving the cutting tool.' The cutting tool, in the nature of a gear, may be built up from a plurality of bladeshaving cutting sides as herein illustrated or a solid gear may.

be constructed as a cutting tool having the flanlm of the teeth provided with lands and grooves for efiecting the cutting edges employed for machin ing the sides of the gear teeth. In like manner comparatively simple, inexpensive machine maybe employed for supporting and effecting the relative movement between my cutter and a gear blank. I

Tools suitable r se in my machine are also described and aimed as such in my copending application, Serial No. 554,192, filed July 31, 1931;

and the method of finishing gears according .to

my invention is claimed in my saidcopending application, Serial No. 554,193, filed July 31, 1931.

In the claims the expression gear-like tool is' used to define a tool of the character of a spur or helical gear which will operate as a driving gear and also as a driven gear. This includes a rack, such as illustrated in the drawing, which is considered here as afcircular gear of infinite radius, having a theoretical axis parallel to the,

pitch surface of the rack teeth about which the rack teeth may be said to rotate. The expression gear-like tool in the claims excludes 'a hob or similar wormlike cutting tool having a 'helix angle so large that it cannot be driven by the gear which it cuts. The plane of movement of the tool referred to in certain ofthe claims is the plane of rotation of a circular tool,

or that plane of movement of a rack tool which is perpendicular to the theoretical axis of the rack and parallel to the path of movement followed by the rack during reciprocation.

Rotation of a pair of gears when in mesh on parallel axes will produce slippage between the meshed teeth in a radial 'or vertical direction, that is perpendicular to the .pitch lines of the meshed teeth. If one of a pair of meshed gears is moved axially with respect to the other without rotation the slippage occurring between the meshed teeth will be lateral in direction, that is, parallel to the pitch lines of the meshed teeth. This latter is true irrespective of whether the gears are on parallel axes or not. when this radial and lateral slippage occur simultaneously, the resulting slippage between the meshed teeth is in a direction diagonally ofthe tooth faces and is the resultant of these two simultaneously acting components of movement. Such simultaneous lateral and radial slippage maybe secured, asin the embodiment of the invention disclosed herein, by rotating the gear in mesh with the tool in a plane at anangle to the plane of movement of the tool, or, as, stated in certain of the. claims, with the axes of the tooland gear at an angle -t each other.- The rolling componentof mov ent is therefore the component which tends to produce slippage between the teeth in adirection perpendicular to the pitch lines of the meshed teeth and the "lateral component of movement is the componentwhich tends to produce slippage in a direction parallel to the pitch' lines of the meshed teeth. The reference to lateral cutting edges" in the claims means cutting edges which out due to the lateral com- I ponent of movement. Such cutting edges, if they extend substantially vertically oi the tool teeth, lie substantiallyparallel-to the plane of roll of the gear and substantially parallel to the vertical or radial component of sliding movement.

Accordingly. vertical or substantially vertical cutting edges are provided so that there will not, be any material cutting resulting from that vertical or radial component of sliding movement.

The terminology substantially vertical cutting,-

edges is intended to include cutting edges which may be somewhat inclined from the vertical but which are not of suflicient inclination to cause material cutting as a result of the vertical or radial component of sliding movement between the gear and tool teeth. Likewise the terminology with'the engaged cutting edges of the tool substantially parallel to the plane of rota ion of the gear" is intended to include a similar variation fromparallelism with the plane of rotation of the gear.

While I have specified that the cutter is actuated to efiect the machining of the gears, it is to be understood that the same result may be obtained by actuating the gear and/or its support across the cutting tool. In either case a gear having extremely accurate tooth profile and spacing is finished, or roughed and finished, by

an operation which utilizes my cutting method.

While I have described and' illustrated several embodiments of my invention, it will be apparent to those skilled in the art that various changes, omissions, additions and substitutions may be made therein without departing from the spirit andscope of my invention, as set forth in the accompanying claims.

I claim:

1. In a machine for finishing roughed out gear teeth utilizing a tool having a plurality of teeth one flank of each of which is formed of a pluralityof spaced lands having substantially parallel lateral cutting edges thereon; the combination of means for supporting said gear and said tool in engaging relation with the said lateral cutting edges in planes substantially parallel to the planeof the roll of the gear relative to the tool; and

means for rolling said gear relative to said tool and for introducing a lateral component of move-' ment between said gear and tool teeth. 2. In a machine for finishing roughedout teeth utilizing a tool having a plurality of teeth one flank of each of which is formed of a plurality of spaced lands having substantially parallel lateral cutting edges thereon,- the combination of means for supporting said gear and said tool in engaging relation with the axes thereof at an angle to each other and with the said lateral cutting edges in planes substantially parallel to the plane of the roll ofthe gear relative to the tool; and means for rolling said gear relative to said tool'thereby introducing a lateral component of movement between said gear and tool teeth.

3. In amachine for finishing roughed out gear teeth utilizing a tool ,having' a plurality of teeth.

one flank of each of which is formed of a plurality of spaced lands having substantially parallel lateral cutting edges thereon, the combination of means for supporting said gear and said tool in engaging telatlon with the said lateral cutting edges in planes substantially parallel to the plane of the roll of the gear relative to the tool; and means for rolling said gear relative to said tool and for introducing a lateral component of movement between said gear and tool teeth; and additional means for feeding said gear radially relative to said tool.

4. In a machine for finishing roughed out teeth utilizing a tool having a plurality of teeth one flank or each of which is formed of a plurality of spaced lands having substantially parallel lateral cutting edges thereon, the combination of means forsupporting said gear and said tool in engag .7

ing relation with the axes thereof at an angle to each other and with the said lateral cutting edges in planes substantially parallel to the plane of the roll of the gear relative to the tool; and means for rolling said gear relative to said tool thereby introducing a lateral component of movement between said gear and tool teeth; and additional means for feeding said gear radially relative to said tool.

5. A machine for finish cutting roughed out gears, comprising, in combination, a gear-like tool having a plurality of teeth conjugate to the teeth to be produced on the gear to be finished, the

' working surfaces of each of the teeth of said tool being provided with a plurality of narrow parallel grooves separated by narrow lands, the edges of said lands forming parallel cutting edges, said grooves and cutting edges extending substantially vertically from the roots of the teeth to the crests thereof, means for operatively supporting the tooland gear in mesh with the engaged cutting edges of the tool substantially parallel to the plane. of

rotation of the gear, means for driving one by the other to bring the cutting edges progressively into contact with the gear teeth. .andmeans for introducing a simultaneous lateral component of movement between the meshed teeth of the gearand tool in a direction transverse to'the' cutting edges incontactwith the gear to effect cutting of the gear teeth by said vertical cutting edges.

6. A machine for finish cutting roughed out gears, comprising, in combination, a gear-like toolhaving a plurality of teethconiuga'te to the teeth to be produced on the gear to be finished, the working surfaces of each of the teeth of said tool bein provided with a plurality of narrow parallel grooves, by narrow lands, the edges of aiaaviv said lands forming parallelcutting edges, said grooves and cutting edges extending substantially vertically from the roots of the teeth to the crests thereof, means for operatively supporting the tool and gear in mesh with the engaged cutting edges or the tool substantially parallel to the plane of rotation of the gear, means for driving one by the other to bring the cutting edgesprogressively into contact with the gear teeth, means for introducing a simultaneous lateral component movement between the meshed teeth of the gear and tool ;in a direction transverse to the cutting edges in contact with the gear to effect cutting of the gear teeth by said vertical cutting edges, and means for feeding the' gear and tool relatively toward each other radially .of the gear to force the cutting edges on oppositely directed faces of the tool teeth simultaneously into engagement with oppositely directed faces on the gear teeth. I

7. A machine for finish cutting roughed out .gears, comprising, in combination, a gear-like parallel grooves separated by narrow lands. the

edges of said lands forming parallel cutting edges, said grooves and cutting edges extending substantially vertically from the roots of the teeth to the crests thereof. means for operatively supporting the tool and gear in mesh with their planes of movement at an angle to each other and with the I engaged cutting edges of the tool substantially parallel to the plane 01 rotation of the gear, means for driving oneby the other to bring the cutting edges progressively'into contact with the gear teethand to cause a simultaneous lateral component of movement between the meshed teeth oi the gear and tool in a direction transverse to the cutting edges in contact with the gear to eiiect wnmmnnsnzmf cutting 01 the gear teeth by'sa'id vertical cutting edges, and means for fee ing the gear and tool relatively toward each other radially of the gear 

